Hey all, I bought a used OEM cat to replace mine. The previous owner had to cut the splined in bolts on the back of the cat that connects them to the exhaust. I managed to hammer them all out, but I need new bolts and nuts now.

Anyone know what size these are? Can I use any old bolts from Home Depot that fit, or is material a concern?

Thanks!

 

Not sure which bolts you are referring to but here's the diagram and parts...

 

It's part #3 in that diagram, 18176-P08-003. $50 shipped for 3 bolts seems a little expensive, wondering if generic hardware will work.

 

Using regular M10 nuts and bolts shouldn't be a problem, that's what I would have done.
Maybe not the cheapest stuff, but 8.8 grade should be more than enough,

 

Just drill or pound out the studs and substitute appropriate size bolts, lock washers, and nuts. Aftermarket cats and test pipes use this method and it works fine. I suspect this was a manufacturing feature, not a performance feature.

-- Chuck

 

If you're feeling super awesome, find stainless hardware. Heck, the local muffler shop will be able to do it easily.

good luck
daryc

 

Should have left the oem ones in there,mine are 14 yrs old and still ok,the other Honda 20 yrs old and still ok..

 

Mcmaster carr sells JIS spec high strength steel class 10.9 flange bolts and flange nuts - same standard honda uses.

Use anti seize to install them and don't be a gorilla when you tighten them. I think they call out 20LB FT....which is probably close to the max torque recommended for those bolts with grease applied.

Or use stainless steel ones and anti seize and a lower torque value. SS won't be as strong....but you're not installing a structural part.